Method of regulating boiler-pressure.



P. 0. KEILHOLTZ- METHOD OF REGULATING BOILER PRESSURE.

' APPLICATION FILED AUG.6.1914.

11 1 @Q5 1 4., v Patented Nov. 16, 1915.

3 SHEETSSHEET 2.

Wifmeeeee Pym WN /(0% y/z j H P. 0. KEILHOLTZ.

METHOD 0F REGULATING BOILER PRESSURE.

APPLICATION FILED AUG.6. 1914.

L160,5H-. Patented N0v.16,1915.

3 SHEETS-SHEET 3.

METHOD OF REGULATING BOILER-PRESSURE.

Specification of Letters Patent.

Patented Nov. 16, 1915.

Application filed August 6, 1914. Serial No. 855,425.

To all whom it may concern Be it known that I, PIERRE O. KEILHOLTZ, a citizen of the United States of America, residing in the city of Baltimore, 'State of Maryland, have invented certain new and useful Improvements in Methods of Regulating Boiler-Pressure, of which the following is a specification.

This invention relates to a method of controlling the pressure of steam boilers and generators. Such regulation has in the past been found imperfect because there 1s a considerable lag incident to its operation. The period of time which elapses between the change of draft and the building up of the fire to the temperature requisite to give the desired boiler pressure is an element, but more important than this is the lapse of time between the increase of the furnace temperature to this point and the increase of boiler pressure to normal or the point of regulation. The effect of the lag made up of both these-elements is hunting of the regulator or a continued fluctuation of the boiler pressure above and below the normal pressure, or point of regulation. When the regulator owing to a drop in the boiler pressure due to increased load and steam consumption within the capacity of the furnace, acts to increase the draft, a considerable period of time elapses before the pressure of the boiler reaches the point of regulation. As the increased draft is continued through this period, the temperature of the furnace continues to increase until it becomes higher than is necessary to supply the demand and maintain the pressure for which the regulation is set, so that the boiler pressure mounts above the point of regulation and theregulator acts in the opposite phase, the fire being then cooled so that the boiler pressure drops to and below normal and the regulator must again act to increase the fire and the boiler pressure. This is the hunting difficulty as it has been encountered in the various attempts at regulation, and the object of the present invention is to evolve a method for controlling a steam generator, which shall not be subject to this defect.

The steam plant to which my method has been applied includes a compressor .or

blower, or rather a battery of blowers by means of which a forced draft is established and the control operates through and in connection with the blowers, though it may be otherwise applied within the scope of the invention and 21h automatic stoker may be operated with the blower and thus utilized as part of the control. In they present instance, the blowers are driven each by a separate electric motor, and one or any number of blowers or compressors may be utilized dependmg upon the capacity of the plant and of the individual blowers.

The method which is the subject of my invention. consists in controlling the steam generator to maintain the desired steam pressure by varying the draft, or both the draft andfuel feed, and causing the draft pressure to react upon and control and check the action resulting from the variation in steam pressure. The apparatus by means of which it is carried out in the present instance consists of a regulator which operates in response to the boiler pressure to increase or decrease the draft, the regulator being in turn controlled by the reaction of the draft pressure so that it is returned to normal and thus discontinues the regulating operation as soon as the variation in draft thus produced reaches a point where it corresponds to the existing variation of boiler pressure from the point of regulation. In the form of the apparatus shown, there is a regulator actuated by the variation of the boiler pressure above and below normal, the same being connected to the draft creating elements to increase or decrease the draft to compensate for the decrease or increase of boiler pressure, the regulator which is controlled by the boiler pressure being in turn connected to a member which is actuated by the variation in draft pressure so that the regulator is stopped or returned to normal when the variation in draft pressure thus produced corresponds to the variation in boiler pressure andsteam consumption.

The apparatus used in the practice of the method may be widely varied within the scope of my invention but 'in order that the nature and operation of the invention may be understood, a steam plant and control embodying an apparatus by means of which the method of the invention may be carried out are illustrated in the accompanying drawings, in which Figure 1 is a diagrammatic view of the steam plant and regulator; Fig. 2 is an elevation showing the regulator proper; Fig. 3 is an elevation taken at right angles to Fig. 2; and Fig. 4 is a detail view. Fig.

' ing 5 is a horizontal section taken just above the axis of the roller in Fig. 2 on the line 5,

5, of said figure;

Referring to the drawing; by numerals, each of which is used to indicate the same or similar parts in the different figures, the illustration includes a boiler furnace 1 and blowers 2 delivering. air under pressure beneath the grate by means of delivery pipe 3. The blowers may be of any desired number; in the present instance, there are six, each being driven from a suitable source of power, for which purpose I have illustrated an individual motor 4 in connection with each blower. Preferably there is also an automatic stoker 6, the stoker being driven from or connected to the corresponding blower as by a belt 6'.

The regulator consists of a diaphragm 5 to which the boiler pressurev is communicated by means of a pipe 7 The diaphragm carries an upwardly disposed lmife edge or equivalent element 8 which acts upon a horizontal leveror regulating member 9 pivoted at 10. The lever 9 carries a weight 11 which is adjustable toward and from'the pivot and a suspended weight 12 which preferably consists of a plurality of small weights 13 so that the amount of. the weight may be changed to conform to the desired pressure or other variable quantities, the weight being used to counterbalance the steam pressure on the diaphragm. When the upward pressure on the diaphragm decreases below normal or the point of regulation, the weights tend to,

swing the lever downward, and when'it in creases above normal, the long arm moves upward. The lever or regulating'member 9 also carries an inverted bell jar 14, in this instance pivota'lly connected at 15 to the outer end of the lever, the inverted'bell jar 14: being inclosed within an upright jar 16, the jar beingpartially filled with water to a level which w1ll be assumed at the height of the broken line 17, the space in the inverted bell 14 above the liquid level being connected by means of a pipe 18 to the throat or delivery pipe of the blower or draft creating element at 19. To give the necessary control of the blowers, the lever 9 is connected by means of a rod 20 includa link 21, to a second horizontal lever 22 which in turn is pivotally connected to the swinging end 23 of a bell crank lever 24 mounted on a stationary pivot 25, and

' the lever 22 is connected by means of arod 26 to a 'pilot valve 27 which controls the flow to and from the fluidpressure cylin der 28. The valve 27 which is a commercial article and need not be specifically 'de-' scribed, has two connections, one to the pressure pipe 29 and one to the outlet or relief pipe 30 respectively, and two ports connected to the upper and lower ends of crank lever 24, the same "the wedge by a spring' tl,

. arm

the hydraulic cylinder 28. As the lever 9 swings up, actuated by the raising of the diaphragm 5 due to the increase of boiler pressure, the-rod 26 being likewise moved upward, causes the fluid, usually water under pressure, to enter the lower end of the cylinder 28, the upper end of the cylinder being exhausted through relief pipe 30 and under these circumstances, the piston 31 moves upward. The reverse action of the block of resistance in series with the motors so that when the switch is in, the motor speed and resulting draft, and if so connected, the fuel feed, are definitely increased, and when the switch is out, the motor speed and draft, etol, dependent thereon, are reduced. s v

A dia ram of a circuit for controlling the speed of the motors is shown in connection with Fig. 4. In this figure I have shown positive and negative buses 72 and a and motors 4, 4 with the armatures connected across the buses and the fields F on a shunt containing a series of resistance coils R. In connection with each resistance unit B, there isa switch with contacts a3f by which the corresponding resistance unit may be short circuited. Each switch is actuated by a coil G controlled by a corresponding cam-controlled switch 39 of the series already described. The manner of operation is apparent. As contact is made at each of the series ofswitches 39 the corresponding magnet G switch d-f is closed, the corresponding resistance'R is cut out, motors increased. The reverse is true for the opposite regulation.

In order that there may be a proper is energized, the

and the speed of the check upon the action of the hydraulic cylinde'r, for unless some means were provlde for stopping 1t, the rack would first move upward for the full stroke of the piston, or

until reverse regulation takes place, and then downward for a similar stroke, a wedge 40 is provided. This is suspended from the piston rod and acts on the follower 41 on the depending end of the bell being held against which is com.- pressed between the'yoke41 and the lever 24. When the regulator acts in response to the increased boiler pressure with the rod 32 moving upward, the wedge 40 likewise moving upward in the guide 40,-

whereby the valve 27 is closed and the mo tion of the piston arrested until there is a further action of the regulator giving a step by step action of the regulator until the boiler pressure responds.

The device thus described serves effectually to increase the draft created by the blowers when the boiler pressure drops below agiven point of regulation, and likewise'todecrease the draft when the boiler pressure mounts above the same point, but owing to the time element which is always present, 71.0., the lag of the furnace temperature as compared to the draft, and boiler pressure as compared to the furnace temperature, the regulation thus attained is not sufiiciently accurate, and the regulator hunts with the usual resulting waste of fuel and loss of boiler pressure. To .overcome this difliculty and give the apparatus the desired degreeof accuracy, I have added the compensating element referred to. In the operation of this feature, the draft pressure is immediately communicated to the bell jar 14 in the form of air pressure, and

has an appreciable effect in supporting the weights on the long arm of the lever 9 which tend to swing Ithatlever downward against the pressure communicated from the boiler to the diaphragm 5. Now the downward motion of the long arm of the lever. 9, produces the regulative eflectwhereby the boiler pressure is decreased and the upward motion produces the opposite effect so that if the pressure'of the boiler has risen above normal, the regulation which takes place to .overcome this variation is as follows: The draft, and fuel feed if so con- 'nected, having been decreased by upward motion of the long arm of the lever 9 caused by upward pressure on the.diaphragm 5, the weights 11 and 12 being partially supported by the draft pressure-communicated to the bell jar 14, the regulatin efi'ect prodifced on the draft being imme lately communicated to the bell jar, reduces the air pressure therein and causes the lever 9 to drop correspondingly so that the regulating action, (referring to the draft and fuel feed variation or either), terminates, for the time being, to be continued or repeated if the.

boiler pressure is sufiiciently in excess of the normal to again raise the lever 9 with the supporting effect of the bell jar 14 thus reduced.

It will be noted that the change in fuel ,and air supply is proportionate or substantially proportionate to the variations in steam consumption being compensated. For instance, if there is a largeincrease in boiler pressure, due 'to decreased load or increased furnace temperature the lever 9 is moved well upward and a correspondingly great reduction of the pressure within the jar 14 and a consequent reduction of blower pressure and fuel feed, if the .feed is so con-' nect-ed, is necessary to return the lever 9 to its normal position, thus terminating the regulating effect, for with the lever 9 in this position, the circuits of the motors driving the blowers are returned to normal condition so that the regulating operation or cycle iscompleted to be repeated in case the boiler pressure is not corrected and the variation remains suflicient to again raise the diaphragm and operate the regulating apparatus. ering to the furnace definite predetermined quantities of fuel and air, or air alone. It will also be apparent that with the regulator thus controlled by means of draft pressure, hunting cannot take place for the first effect of the change in blower speed which results from the movement of the lever 9 in response to the change of position of the Thus the operation consistsin delivdiaphragm, is a change of draft pressure which is immediately communicated to the bell jar l4 and to the lever 9, the tendency to move the latter being opposed to the regulating impulse just imparted to it,' so that the parts being properly designed, the regulator'isreturned to normal long before the boiler pressure has responded to the regulating action, and hunting 'or fluctua-. tion of the regulative element 'above and below normal is forestalled and prevented.

l have thus described specifically and in detail my method ofcontrolling the pres sure of a steam boiler, and an apparatus by means of which-the method may be accomplished. This has been done in order that the nature of the invention may be fully understood; however, the specificterms applied herein are usedv descriptively rather than in their limiting sense and the scope 'of the invention is defined in the claims.

' What-l claim and, desire to secure byIietters Patent is; Y I

1. A -method of operating a mechanical apparatus including a steam boiler, a furnace and a pressure regulator, to-control the boiler pressure, the method consisting in supplying varying quantities of fuel and-air back substantially to fuel and air and thus controlling the gener- 3. A method of regulating the generation and pressure of steam in a steam'plant ina steam boiler and a regulator operated by steam pressure to control combustion by varying the generation of heat in the furnace which consists in supcluding a furnace,

plying to the furnace air under pressure in excess of that of the atmosphere, varying the air supply pressure to" compensate for Variations of steam pressure and utilizing these same variations in air supply, pressure to prevent hunting by having them re-act directlyon the air supplying meansfas soon as that pressure varies by, apre-determined amount bringing the air supply pressure thepoint from which regulation started. 7

4:. A method of regulating the generation and pressure of steam in a steam plant including a furnace, a boiler and a pressure regulator by varying the generation of heat in the furnace which consists in supplying of that of the atmosphere, varying the air supply pressure to compensate for variations of steam pressure and utilizing these same variations in air supply pressure to prevent hunting by causing them to re-act directly .on the air supplying means causing the approach the point air supply. pressure to started as soon as from which regulation that pressure varies amount,

" draft apparatus in produced by whereby excessive fluctuations conditions and steam pressure are prevented,

by a pre-determined 5. A method of operating a mechanical draft apparatus, including a steam pressure actuated draft regulator, to regulate combustion and hence steam pressure which consists first in varying the operation of the response to fluctuations in the steam pressure, and second, in causing the variation in air supply pressure produced by the first step to react directly upon the regulator and return the draft apparatus to normal operating condition as soon as the air pressure is varied by a predetermined amount, whereby hunting of furnace conditions is prevented.

6. A method of operating a mechanical draft apparatus including means for creating a forced draft, a motor to drive the same, variations in the steam pressure to control the speed of the motor and a device for checking the operation of the regulator in the form of a connection from the air supply to the regulator, the method consisting first, in regulating the motor by which forced draft is produced to compensate for varia: tions in steam pressure, and second, in caus ing the variations in air supply pressure the first step to re-act upon the a pressure regulator operated by motor and check the regulating action resulting from the variation in boiler pressure of furnace Signed by me at Baltimore, Maryland, this flth day of August 1914.

I PIERRE OIKEILHOLTZ. Witnessesi I EDWARD L. BASH, EDWIN F. SAMonns. 

